Insert control device for prolonged treatment of animals contaning coumaphos and diazinon

ABSTRACT

Annoying insects are controlled by attaching an insect control device to the body of the animal to be treated. The insect control device is a molded article, preferably in the form of an ear tag, which has been formed from a powder mixture of coumaphos and diazinon, polyvinyl chloride, and a plasticizer. The coumaphos and diazinon are generally used in an amount that would prolong the insecticidal activity without detracting from the suitability of the device.

[0001] This application claims benefit of U.S. Provisional ApplicationSerial No. 60/315,406, filed Aug. 28, 2001, the contents of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to an improved insect controldevice for animals especially livestock, a method of making the devices,and a process for protecting livestock against insects for a prolongedperiod.

BACKGROUND OF THE INVENTION

[0003] Livestock are frequently troubled by various types of insectssuch as flies and lice that transmit infection of the skin, eyes, andears as well as cause irritation leading to loss of production. Severalapproaches have been taken to alleviate this insect problem. Oneapproach requires application of an insecticide spray on the livestock.This approach is undesirable because it requires a substantial amount oftime and labor to gather and treat the livestock. Furthermore, thisapproach is effective for only a short period and requires frequentapplications. A more economical and less labor-intensive approach is,therefore, generally preferred.

[0004] Another approach is the application of insecticide by contactingthe target livestock with a device from which an insecticide isdispensed. Dispensers such as dust bags or oilers are placed in areaswhere it is anticipated that the livestock will come into contact withthem. While this approach reduces the amount of labor involved intreating livestock, it does not ensure that each animal will receive thenecessary treatment at regular intervals.

[0005] Yet another approach employs slow release pesticide mixed with aresinous substance that will release the insecticide over an extendedperiod of time. These pesticide-containing resins have been used in avariety of forms ranging from collars to tags that are attached tovarious body parts of the animal. The use of pesticide-containing eartags is of particular interest for treating livestock as is evident fromthe number of patents directed to such ear tags.

[0006] For example, U.S. Pat. Nos. 4,366,777 and 4,562,794 disclose eartags in which a liquid insecticide dispenser is used. In U.S. Patent No.4,366,777, the liquid insecticide is enclosed in a fibrous or foamreservoir wicked onto the surface of the tag. In U.S. Pat. No.4,562,794, the dispenser or reservoir containing the insecticide isattached to an animal identification tag. Release of the insecticide isdependent upon migration or diffusion of the insecticide through asemi-permeable membrane.

[0007] U.S. Pat. No.4,428,327 discloses an insecticide-impregnated tapethat is attached to a conventional ear tag. Each of these tags has beenfound to be disadvantageous because the insecticide containing reservoiror tape may be detached from the tag by fences or brush. It would,therefore, be advantageous to have a tag in which the insecticide isdirectly incorporated.

[0008] Such an approach is disclosed in U.S. Pat. Nos. 4,721,064;4,195,075; and 4,265,876 as well as in Miller et al., (“Release ofPyrethroids from Insecticidal Ear Tags,” J. Econ. Entomol. 76:1335-1340,1983) and Miller et al., (“Release Rates from Cattle Insecticidal EarTags in Various Regions of the United States,” The SouthwesternEntomologist, Vol. II(1), pages 45-50, March 1986). The Miller et al.disclosures and U.S. Pat. No. 4,195,075 are, however, limited to liquidinsecticides which can evaporate at ambient temperatures. Use of suchliquid insecticides may be undesirable in areas where the ambienttemperature is high enough to cause rapid evaporation of the insecticideand thus, result in an undesirably greater release of insecticide over ashorter period of time.

[0009] More specifically, U.S. Pat. No. 4,265,876 is limited to tagscontaining pyrethroid insecticides whereas coumaphos is not apyrethroid. U.S. Pat. No. 5,018,481 discloses an insect control device,attachable to the body of a target animal, that has been formed from apowder mixture of coumaphos, polyvinyl chloride, and a plasticizer. Thecoumaphos is used in an amount of 5 to 30% of the device.

[0010] In order for the device to have a prolonged use of about four ormore months of effective control of insects especially on cattle, alarge concentration of insecticide must be incorporated into thecarrier. If too much insecticide is used in plastic molded carriers, forexample, in the form of ear tags, they become unsuitably soft. By thepresent invention, there is provided a suitable device for providingprolonged and effective insecticidal activity.

SUMMARY OF THE INVENTION

[0011] In accordance with the foregoing, the invention encompasses aninsect control device for livestock which effectively releases insectcontrolling agent for a period of about four or more months. That is, asufficient quantity of insect controlling agent is released to provideefficacious control of insects. In its present embodiment, the device isin the form of an ear tag comprising a molded article formed from amixture of an effective combination of the active ingredients, coumaphosand diazinon, polyvinyl chloride, and a plasticizer. By an effectivecombination is meant that the coumaphos and diazinon are employed in anamount sufficient to provide insecticidal activity. To be sure, whilecoumaphos and diazinon are known as insecticides, it has been surprisingto obtain results of prolonged treatment with a device containing thecombination of solid coumaphos with liquid diazinon in accordance withthis invention. An amount of about 10 to about 60 percent by weight andpreferably about 25 to about 40 percent by weight of the activeingredients based on the total weight of the device may be employed. Ofthis amount about 10 to about 30 percent by weight and preferably about20 to about 25 percent by weight may be coumaphos, and about 10 to about30 percent by weight and preferably about 20 to about 25 percent byweight may be diazinon.

[0012] The active ingredients may be incorporated into any compatiblematerial which can carry the active ingredients at high loads withoutbeing rendered unsuitable in their handling or performance in theservice environment. Moreover, the material should be such as wouldreleasably contain the active ingredients. The phrase “releasablycontain” means that the active ingredient, while in the compatiblematerial, is disposed to contact an insect that comes into contacttherewith.

[0013] In one embodiment, the present invention encompasses a suitableear tag having a high concentration of insecticide that is effective forabout four or more months. By the term “suitable” is meant that thematerial of the device retains its integrity as to handling orperformance in the service environment. Illustratively, a plastic moldedear tag does not become tacky and continues to release insecticides fora prolonged period.

DETAILED DESCRIPTION OF THE INVENTION

[0014] As set forth above, the insect control devices of the presentinvention are formed from a mixture of an effective combinationcoumaphos and diazinon, polyvinyl chloride, and a plasticizer. Coumaphosis a solid organophosphorous insecticide which is effective againstarthropods including flies, grubs, lice, ticks, and mites. In thedevices of the present invention, coumaphos is generally present in anamount of from about 3 to about 30 wt % of the total weight of thedevice, preferably in an amount of from about 10 to about 25 wt %, andmost preferably in an amount of from about 10 to about 15 wt %. Diazinonis a liquid organophosphorous insecticide which is also effectiveagainst arthropods including flies, grubs, lice, ticks, and mites. Inthe devices of the present invention, diazinon is present in an amountof about 10 to about 30% by weight and preferably about 20 to about 25%by weight based on the total weight of 10 to 20 g.

[0015] It is, of course, possible to include other known insecticides inthe mixture from which the insect control devices of the presentinvention are formed. The other known insecticides should be such aswould not detract from the insecticidal activity or detract from thesuitability of the device.

[0016] Polyvinyl chloride is generally present in the devices of thepresent invention in an amount of from about 30 to about 70 wt % of thetotal weight of the device, preferably in an amount of from about 40 toabout 60 wt %, and most preferably from about 45 to about 55 wt %.

[0017] The plasticizer used in making the insect control devices of thepresent invention may be any of the known plasticizers. Specificexamples of suitable plasticizers include: phthalates such as dioctylphthalate, diphenyl dimethyl phthalate, and dihexyl phthalate; sebacatessuch as dipentyl sebacate, n-butyl benzyl sebacate, and dibenzylsebacate; adipates such as dioctyl adipate, dicapryl adipate,di-isobutyl adipate, and dinonyl adipate; hydrogenated polyphenols;alkylated aromatic hydrocarbons; and polyester plasticizers such aspolyesters of polyols and polycarboxylic acids having a molecular weightof at least 2000. The plasticizer is present in an amount of from 0 toabout 30 wt % of the total weight of the insect control device,preferably from about 5 to about 25 wt %, and most preferably from about10 to about 25 wt %.

[0018] Other materials such as dyes, pigments, lubricants, lakes,fillers, anti-oxidants, and ultraviolet stabilizers may optionally beincluded in the mixture from which the insect control devices of thepresent invention are formed. If these materials are included, they aregenerally present in an amount of from about 1 to about 10 wt %,preferably in an amount of from about 2 to about 4 wt %.

[0019] In a method for preparing the device, the solid coumaphos andliquid diazinon are incorporated as follows. The polyvinyl chloride andplasticizer are mixed together and heated to a temperature of about 180°F. The diazinon is then added and the mixture is blended for 3 hours.The mixture is then allowed to cool to 68 to 80° F. (ideal 72° F.). Thecoumaphos and other ingredients are then added and blended for 2 hours.The mixture containing coumaphos, diazinon, polyvinyl chloride,plasticizer and optional ingredients is a mixture of solids which ismolded, preferably by injection molding, to the desired form. Thepreferred forrn is an ear tag which may be attached directly to the earof livestock. Techniques for molding such mixtures are known to thoseskilled in the art. One such molding method is disclosed in U.S. Pat.No. 4,195,075. Techniques for attaching the molded insect control deviceto an animal, such as livestock, are also well known in the art. As usedherein, the term “livestock” is intended to include cattle, sheep, pigs,horses, and other animals.

EXAMPLES

[0020] The present invention is further illustrated by the followingexamples which should not be construed as limiting in any way.

Example 1

[0021] 3712 g of polvinyl chloride and 119 g of acetyl tributyl citratewere combined and heated to 180° F. Technical diazinon (1907 g) wasadded to the mixture and blended for 3 hours. The mixture was allowed tocool for 8 hours: 1906 g of technical coumaphos and 95 g of titaniumdioxide were added and mixed for 2 hours. Ear tags were produced bypassing the mixture through an injection molding procedure at 250° F. toproduce individual ear tags weighing 14-15 g containing 18.7%plasticizer, 20% coumaphos, and 20% diazinon.

Example 2

[0022] 4234 g of polyvinyl chloride and 1389 g of acetyl tributylcitrate were combined and heated to 180° F. Technical diazinon (1906 g)was added to the mixture and blended for 3 hours. The mixture wasallowed to cool for 8 hours: 1906 g of technical coumaphos and 95 g oftitanium dioxide were added to the mixture and blended for 2 hours. Eartags were produced by passing the mixture through an injection moldingprocedure at 250° F. to produce individual tags weighing 14-15 gcontaining 13.6% plasticizer, 20% coumaphos, and 20% diazinon.

Example 3

[0023] 4667 g of polyvinyl chloride and 956 g of acetyl tributyl citratewere combined and heated to 180° F. Technical diazinon (1906 g) wasadded to the mixture and blended for 3 hours. The mixture was allowed tocool for 8 hours: 1906 g of coumaphos and 95 g of titanium dioxide wereadded and blended for 2 hours. Ear tags were produced by passing themixture through an injection molding procedure at 250° F. to produceindividual tags weighing 14-15 g containing 9.4% plasticizer, 20%coumaphos, and 20% diazinon.

Example 4

[0024] 4878 g of polyvinyl chloride and 318 g of expoxidized soybean oilwere combined and blended at approximately 180° F.: 2738 g of technicaldiazinon was added and blended for 3 hours. The mixture was cooled to72° F.: 1500 g of coumaphos and 95 g of titanium dioxide were added andblended for 2 hours. Ear tags were produced by passing the mixturethrough an injection molding procedure at 250° F. to produce individualtags weighing 14-15 g containing 15% coumaphos and 25% diazinon.

Example 5

[0025] Determination of the Depletion Rate of Coumaphos+Diazinon fromCattle Ear Tags.

[0026] The ear tags produced in Examples 1-3 were attached to the earsof cattle for a period of 20 weeks. Tags were removed from animals atpre-determined intervals, weighed, and analyzed to determine thequantity and release rate of active ingredient from the molded tags. Theresults are displayed below in Table 1. TABLE 1 Depletion Rate of ActiveIngredients Weeks After (Coumaphos + Diazinon) Application to From EarTags (mg/day) Cattle TAG A TAG B TAG C 4 61.3 30.0 50.0 8 51.0 70.0 32.312 19.1 3.0 17.1 16 4.6 4.9 0 20 4.6 17.8 11.4

[0027] The results of this study demonstrate that coumaphos and diazinonare released together from the molded ear tags for at least 20 weeksafter application to cattle. The greatest release rate was observed forthe first 8 weeks after application.

Example 6

[0028] Determination of the Effectiveness of Coumaphos+Diazinon Ear Tagsto Control Flies on Cattle.

[0029] The ear tags produced in Examples 1-3 were attached to the earsof cattle in herds located in Kentucky, Nebraska, and Missouri (one ortwo tags/animal). The mean number of horn flies (Haematobia irditans)and/or face flies (Musca autumnalis) per animal was determined prior toapplication of the ear tags. The cattle were observed at weeklyintervals for up to 17 weeks after tags were applied and fly counts wereperformed. Percent efficacy was calculated by comparing the mean numberof horn (or face) flies per animal on the ear tag treated herds with themean number of flies on adjacent untreated cattle according to thefollowing formula. $\begin{matrix}{{Percent}\quad} \\{Efficacy}\end{matrix} = {\frac{\begin{matrix}{{mean}\quad {{no}.\quad {flies}}\quad {on}\quad {untreated}\quad {animals}} \\{{{- {mean}}\quad {{no}.\quad {flies}}\quad {on}\quad {ear}\quad {tag}}\quad} \\{{treated}\quad {animals}}\end{matrix}}{{mean}\quad {{no}.\quad {flies}}\quad {on}\quad {untreated}\quad {animals}} \times 100}$

[0030] The results are displayed below in Tables 2-4. TABLE 2 Kentucky*Horn Flies Face Flies Mean No. Mean No. Flies/ % Flies/ Animal EfficacyAnimal % Efficacy Pre- 62.0 — 30.5 — Treatment Weeks Post- Treatment  10 100 11.8 56.3  2 0 100 8.8 68.6  3 0 100 7.2 66.5  4 0 100 6.7 73.2  50 100 8.2 61.9  6 0 100 1.7 87.5  7 0 100 2.7 74.0  8 0 100 1.9 79.3  90 100 2.6 70.8 10 0 100 2.9 57.4 11 0 100 2.1 70.8 12 0 100 2.9 59.2 130 100 4.9 29.0 14 0 100 3.7 50.0 15 4 99.1 3.3 53.5

[0031] TABLE 3 Missouri* Horn Flies Face Flies Mean No. Mean No. Flies/% Flies/ Animal Efficacy Animal % Efficacy Pre- 32.1 — 1.4 — treatmentWeeks Post- treatment  1 1 99 0.5 81  2 0 100 0.4 90  3 0 100 2.8 84  40 100 9.7 45  5 0 100 4.6 75  6 0 100 3.1 84  7 0 100 5.2 57  8 0 1004.1 87  9 0 100 6.4 82 10 0 100 10.3 61 11 0 100 15.9 50 12 2 99 14.6 5513 5 99 21.5 37 14 75 85 24.0 0 15 77 84 23.0 22 16 75 72 21.2 5

[0032] TABLE 4 Nebraska* Horn Flies Mean No. Flies/ Animal % EfficacyPre-treatment 248 — Weeks Post- treatment  1 — —  2 36 86  3 49 87  4 4093  5 32 94  6 105 79  7 49 92  8 41 95  9 62 87 10 57 90 11 58 91 12 6990 13 119 81 14 385 38 15 234 45 16 420 26 17 61 52

[0033] The results of these studies demonstrated that coumaphos anddiazinon are depleted from the ear tag devices described in Examples 1-3at sufficient quantity to provide efficacious control of horn and faceflies on cattle for at least 17 weeks.

[0034] Althought the invention has been described in detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be limited by the claims.

What is claimed is:
 1. An insect control device for attachment toanimals which effectively releases insect controlling agents for aperiod of up to about four months comprising a molded article formedfrom a mixture of coumaphos and diazinon, polyvinyl chloride, and aplasticizer.
 2. The device of claim 1, wherein coumaphos and diazinonare present in an amount of from about 10 to about 60 wt % of the totalweight of the device.
 3. The device of claim 2, wherein coumaphos anddiazinon are present in an amount of from about 30 to about 50 wt % ofthe total weight of the device.
 4. The device of claim 1 or 2, whereinthe article is in the form of an ear tag.
 5. The device of claim 2,wherein coumaphos is present in an amount of from about 3 to about 30 wt% of the total weight of the device.
 6. The device of claim 2, whereindiazinon is present in an amount of from about 10 to about 30 wt % ofthe total weight of the device.
 7. The device of claim 2, whereinpolyvinyl chloride is present in an amount of from about 30 to about 70wt % of the total weight of the device.
 8. The device of claim 7,wherein a plasticizer is present in an amount of from about 0 to about30 wt % of the total weight of the device.
 9. The device of claim 8,wherein the plasticizer is selected from the group consisting ofphthalates, sebacates, adipates, hydrogenated polyphenols, alkylatedaromatic hydrocarbons, and polyesters.
 10. The device of claim 7,wherein the mixture to be molded also includes up to about 5 wt %stabilizer.
 11. The device of claim 10, wherein the mixture to be moldedalso includes up to about 5 wt % pigment or lake.
 12. The device ofclaim 11, wherein the article is in the form of an ear tag.
 13. Thedevice of claim 1, wherein coumaphos is present in an amount of fromabout 3 to about 30 wt %, diazinon is present in an amount of from about10 to about 30 wt %, polyvinyl chloride is present in an amount of fromabout 30 to about 70 wt %, and a plasticizer is present from 0 to about30 wt % of the total weight of the device.
 14. The device of claim 13,wherein the article is in the form of an ear tag.
 15. The device ofclaim 13, wherein the mixture to be molded also includes up to about 5wt % stabilizer.
 16. The device of claim 15, wherein the mixture to bemolded also includes up to about 5 wt % pigment or lake.
 17. A processfor treating livestock to control insects comprising the step ofattaching the device of claim 1 to an ear of an animal to be treated.18. The process of claim 17, wherein livestock include cattle, sheep,pigs, and horses.
 19. A process for treating livestock to controlinsects comprising the step of attaching the device of any of claims 4,12, or 14 to an ear of an animal to be treated.
 20. The process of claim19, wherein livestock include cattle, sheep, pigs, and horses.